Method for processing sputtering target and method for manufacturing sputtering target product

ABSTRACT

Disclosed is a method for processing a sputtering target comprises: processing a sputtering target by rotating a cutting tool which has a blade portion with an arc-shaped concave curved surface on a cross section along the axis, around an axis thereof, to chamfer the target at a corner portion between a sputtering surface and a side surface in the sputtering target with an arc-shaped concave curved surface of a blade portion in such a manner that the corner portion is approximated to an arc-shaped aimed R face, wherein the sputtering target is chamfered at the corner portion in such a manner that a curvature radius Ra of the concave curved surface in the blade portion is equal to or more than a curvature radius Rb of the aimed R face on the cross section along the axis and that both ends of the concave curved surface in the blade portion are positioned away from the sputtering target.

TECHNICAL FIELD

The present invention relates to a method for processing a sputteringtarget and a method for producing a sputtering target product.

BACKGROUND ART

With regard to a sputtering target, there has been proposed a processingmethod in which a corner portion between a sputtering surface and a sidesurface in the sputtering target is chamfered to form an R face bymachining (see Patent Document 1).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP 2001-40471 A

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

It is an object of the present invention to provide a method forprocessing a sputtering target and a method for producing a sputteringtarget product both of which method can make an R face approximated toan aimed R face.

Means for Solving the Problems

A method for processing a sputtering target according to the presentinvention comprises:

processing a sputtering target by rotating a cutting tool which has ablade portion with an arc-shaped concave curved surface on a crosssection along the axis, around an axis thereof, to chamfer the target ata corner portion between a sputtering surface and a side surface in thesputtering target, with the arc-shaped concave curved surface of theblade portion in such a manner that the corner portion gets approximatedto an arc-shaped aimed R face, wherein the sputtering target ischamfered at the corner portion in such a manner that a curvature radiusRa of the concave curved surface in the blade portion is equal to ormore than a curvature radius Rb of the aimed R face on the cross sectionalong the axis and that both ends of the concave curved surface in theblade portion are positioned away from the sputtering target.

According to a method for processing a sputtering target in accordancewith the present invention, the sputtering target is chamfered at thecorner portion in such a manner that a curvature radius Ra of theconcave curved surface in the blade portion is equal to or more than acurvature radius Rb of the aimed R face on the cross section along theaxis and that both ends of the concave curved surface in the bladeportion are positioned away from the sputtering target. It can make an Rface approximated to an arc-shaped aimed R face and prevent the facefrom being scratched when cutting a sputtering target at a cornerportion with an arc-shaped concave curved surface of a blade portion.

A method for processing a sputtering target according to the presentinvention also includes

processing a disc-shaped or cylindrical sputtering target by rotatingthe target around the central axis thereof to chamfer the target at acorner portion between a sputtering surface and a side surface in therotating sputtering target with an arc-shaped concave curved surface ofa blade portion in such a manner that the corner portion getsapproximated to an arc-shaped aimed R face,

wherein the sputtering target is chamfered at the corner portion in sucha manner that a curvature radius Ra of the concave curved surface in theblade portion is equal to or more than a curvature radius Rb of theaimed R face on the cross section along the axis and both ends of theconcave curved surface in the blade portion are positioned away from thesputtering target.

According to the method for processing a sputtering target in accordancewith the present invention, a disc-shaped or cylindrical sputteringtarget is rotated around the central axis to being chamfered at itscorner portion in such a manner that a curvature radius Ra of theconcave curved surface in the blade portion is equal to or more than acurvature radius Rb of the aimed R face on the cross section along theaxis and that both ends of the concave curved surface in the bladeportion are positioned away from the sputtering target.

It can make a disc-shaped or cylindrical sputtering target chamfered atits corner portion efficiently and prevent the face from being scratchedwhen cutting a sputtering target at a corner portion with an arc-shapedconcave curved surface of a blade portion.

In this method, a curvature radius Ra of the concave curved surface inthe blade portion is more than a curvature radius Rb of the aimed R faceon the cross section along the axis so that preventing an R face frombeing scratched can efficiently be realized.

In an embodiment of the method for processing a sputtering target, thesputtering target is chamfered at the corner portion in such a mannerthat both the ends of the concave curved surface in the blade portionare positioned away from the sputtering target, and that, in acoordinate system in which a center point Cb of the aimed R face is setas an origin, a [mm] is a gap of a first center point Cl of the concavecurved surface with the curvature radius Ra of the blade portion fromthe center point Cb of the aimed R face in each of horizontal andvertical directions on the coordinate system, Ra, Rb, and a are set tosatisfy the following conditions:

with regard to an intercept L [mm] of an R face, the relationship ofRb/2≤L≤Rb is satisfied when L is represented by the formula ofL=Rb−Ra{1−(Rb−a)²/Ra²}^(1/2)−a;

with regard to an angle θ [rad] formed between the sputtering surface ofthe sputtering target and an end portion of the R face of the sputteringtarget, the relationship of 0≤θ≤π/6 is satisfied when the angle θ [rad]is represented by the formula of θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2); and

with regard to a distance d [mm] between an end portion of the concavecurved surface in the blade portion and the sputtering surface of thesputtering target, the relationship of 0.05≤d is satisfied when thedistance d [mm] is represented by the formula of d=Ra−Rb+a.

Here, the value “a” is a negative value when Cb is set as the origin andC1 is located more on the inner side of the sputtering target than Cb,and a positive value when C1 is located more on the outer side of thesputtering target than the origin Cb.

According to the embodiment, the following relationships are satisfied:Rb/2≤L≤Rb, 0≤θ≤π/6, and 0.05≤d. Accordingly, the R face can further beapproximated to the aimed R face and prevented from being scratched.

A method for producing a sputtering target product includes a step ofprocessing a sputtering target using the method for processing asputtering target.

According to the embodiment, the sputtering target product is producedby the above method for processing a sputtering target so that asputtering target product with fewer scratches to the R face can beprovided.

Effects of the Invention

According to the present invention, when the sputtering target is cut tobe chamfered at a corner portion thereof with a concave curved surfaceof a blade portion to form an R face, the R face can be approximated toan aimed R face and be prevented from being scratched.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a first embodiment of a methodfor processing a sputtering target according to the present invention.

FIG. 2 is a cross-sectional view illustrating the first embodiment ofthe method for processing a sputtering target.

FIG. 3 is an enlarged cross-sectional view of FIG. 2.

FIG. 4 is a perspective view illustrating a second embodiment of amethod for processing a sputtering target according to the presentinvention.

FIG. 5 is an enlarged view illustrating the sputtering target.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be described in detail below withreference to the accompanying drawings.

First Embodiment

FIG. 1 is a perspective view illustrating a first embodiment of aprocessing method according to the present invention. FIG. 2 is across-sectional view illustrating an embodiment of the processing methodaccording to the present invention. As illustrated in FIGS. 1 and 2, inthe method for processing a sputtering target, a sputtering target 1 ischamfered at a corner portion 4 formed between a sputtering surface 2and a side surface 3 into an R face 5 using a cutting tool 10.

The sputtering target 1 is formed in an elongated plate shape. Thesputtering surface 2 is constituted of an upper surface defined by ashort side direction and a long side direction. The side surface 3 isconstituted of a surface defined by the sputtering surface 2 and thethickness direction of the sputtering target. Each corner portion 4 isconstituted of a side defined by the sputtering surface 2 and the sidesurface 3. The sputtering target 1 may be formed in a disk shape. Inthis case, the sputtering surface 2 is constituted of a circular uppersurface, and the side surface 3 is constituted of a circumferentialsurface between the circular upper surface and the circular lowersurface.

The sputtering surface 2 of the sputtering target 1 receives inert gasthat has been plasmatized (or ionized) by sputtering. When inert gasparticles collide with the sputtering surface 2 of the sputtering target1, target atoms contained in the sputtering target 1 are sputtered andejected from the sputtering surface 2. The sputtered atoms are depositedon a substrate facing the sputtering surface 2 to thereby form a thinfilm on the substrate.

The sputtering target 1 can be made of a material selected from thegroup consisting of metals, such as aluminum (Al), copper (Cu), chromium(Cr), iron (Fe), tantalum (Ta), titanium (Ti), zirconium (Zr), tungsten(W), molybdenum (Mo), niobium (Nb), indium (In), and alloys thereof.However, the material constituting the sputtering target 1 is notlimited thereto.

The material constituting the sputtering target 1 for an electrode or awiring material is preferably Al, more preferably Al having a purity of99.99% or more, and still more preferably Al having a purity of 99.999%or more. The high-purity Al is suitable as the material of the targetmaterial 1 for an electrode or a wiring material because of its highelectrical conductivity. As Al becomes higher in purity, Al materialsbecome softer to easily deform the Al material. Therefore, a methodaccording to the present invention can be suitable for producing thetarget material with the high-purity Al.

Examples of the cutting tool 10 include an end mill, a radius cutter, anR cutter, and the like, and in a processing device where the cuttingtool 10 is installed, with the sputtering target 1 fixed, the cornerportion of the sputtering target 1 is chamfered by moving the rotatingcutting tool 10. Examples of this type of processing device includemilling machines, NC milling machines, machining centers, and the like.

The cutting tool 10 includes a shaft portion 11 rotatable around an axis11 a and a blade portion 12 provided at a leading end of the shaftportion 11. The central axis of the blade portion 12 coincides with theaxis 11 a of the shaft portion 11. Two or three blade portions 12 may bepresent around the axis 11 a independently from each other.Alternatively, the blade portions 12 may be continuously present aroundthe axis 11 a. Alternatively, the blade portion 12 may be formedintegrally with the shaft portion 11 or may be formed as a replaceablechip. The cutting tool 10 is arranged with respect to the sputteringtarget 1 such that the axis 11 a coincides with the thickness directionof the sputtering target 1. Then, the cutting tool 10 is moved in thecircumferential direction (the extending direction of the corner portion4) of the sputtering surface 2 of the sputtering target 1 while rotatingaround the axis 11 a, whereby the blade portion 12 of the cutting tool10 sequentially cuts the corner portion 4 of the sputtering target 1.Thereby, the corner portion 4 is chamfered into the R face 5 as theprocessed surface.

FIG. 3 is an enlarged cross-sectional view of FIG. 2. As shown in FIG.3, an outer circumferential surface of the blade portion 12 includes anarc-shaped concave curved surface 20 that extends from the trailing endto leading end of the blade portion 12 on its cross section along theaxis 11 a. The concave curved surface 20 is formed with the axis 11 apositioned as the central axis. Two or three concave curved surfaces 20may be present independently from each other or continuously present.Alternatively, the blade portion 12 may be formed integrally with theshaft portion 11 or may be formed as a replaceable chip. The concavecurved surface 20 is an arc surface of a quarter (¼) of an exact circle.The concave curved surface 20 includes a first end 21 on the leading endside and a second end 22 on the trailing end side. The leading end siderefers to the side of the concave curved surface 20 where the sputteringtarget 1 is processed at the side surface 3, whereas the trailing endside refers to the side of the concave curved surface 20 where hesputtering target 1 is processed at the sputtering surface 2.

Furthermore, the outer circumferential surface of the blade portion 12includes a side surface 30 extending in parallel to the axis 11 a. Theblade portion 12 includes a leading end surface 31 that intersects theaxis 11 a. The first end 21 of the concave curved surface 20 isconnected to the leading end surface 31. The second end 22 of theconcave curved surface 20 is connected to the side surface 30.

The number of blades installed around the axis 11 a is preferably two tofour. As the applicable processing conditions, the rotational speed ofthe blade portion 12 is preferably 100 to 10,000 rpm, and the tool feedspeed is preferably 100 to 3,000 mm/min.

Next, a method for processing a sputtering target 1 will be described.

As shown in FIG. 3, a sputtering target 1 is processed by rotating acutting tool 10 around the axis 11 a, cutting the sputtering target 1 ata corner portion with a concave curved surface 20 of a blade portion 12to be chamfered so as to be approximated an aimed R face 105 having anarc shape, thereby forming an R face 5 in the sputtering target 1. Here,the aimed R face 105 is indicated by a two-dot chain line in FIG. 3. Acurvature radius Rb of the aimed R face 105 is a predetermined value.

Here, the sputtering target 1 is chamfered at the corner portion in sucha manner that a curvature radius Ra of the concave curved surface 20 ofthe blade portion 12 is equal to or more than the curvature radius Rb ofthe aimed R face 105, and preferably more than the curvature radius Rbon the cross section along the axis 11 a, the end portions 21 and 22 ofthe concave curved surface 20 in the blade portion 12 are positionedaway from the sputtering target 1. Consequently, the curvature radius ofthe R face 5 becomes substantially the same as the curvature radius Ra.Gaps d are formed between each of the end portions 21 and 22 of theconcave curved surface 20 and the sputtering target 1. The gap d formedbetween the sputtering target 1 and the end portion 21 of the concavecurved surface 20 may differ in size from the gap d formed between thesputtering target 1 and the end portion 22 thereof.

Specifically, a first center point C1 is defined as the center of theconcave curved surface 20 with the curvature radius Ra in the bladeportion 12 when the corner portion of the sputtering target 1 ischamfered in such as manner that the respective end portions 21 and 22of the concave curved surface 20 in the blade portion 12 are positionedaway from the sputtering target 1. Here, the position of the concavecurved surface 20 in the blade portion 12 is indicated by a solid linein FIG. 3.

A center point Cb is defined as the center of curvature of the aimed Rface. A second center point C2 is defined as the center of curvature ofthe concave curved surface 20 with the curvature radius Ra in the bladeportion 12 when the sputtering target 1 is chamfered at the cornerportion so as to pass the concave curved surface 20 of the blade portion12 through both ends of the aimed R face. Here, the position of theconcave curved surface 20 in the blade portion 12 is indicated by adotted line in FIG. 3.

Then, the first center point C1 is shifted toward the corner portionside of the sputtering target 1 with respect to the second center pointC2.

In a coordinate system with the center point Cb of the aimed R face setas the origin, an intercept L [mm] of the R face is represented by theformula below: L=Rb−Ra{1−(Rb−a)²/Ra²}^(1/2)−a, and satisfies therelationship below: Rb/2≤L≤Rb where a [mm] is a gap of the first centerpoint C1 from the center point Cb of the aimed R face in each of thehorizontal and vertical directions on the coordinate system when thesecond center point C2 is moved to the first center point C1. Forexample, when Ra=3.5 mm, Rb=3 mm, and a=−0.4 mm, the following valuesare determined: Rb/2=1.5 mm, L=2.6 mm, and Rb=3 mm. Consequently, thefollowing relationship is satisfied: Rb/2≤L≤Rb.

An angle θ [rad] formed between the sputtering surface 2 of thesputtering target 1 and an end portion of the R face 5 of the sputteringtarget 1 is represented by the formula below:θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2), and satisifies the relationship below:0≤θ≤π/6.

For example, when Ra=3.5 mm, Rb=3 mm, and a=−0.4 mm, the followingvalues are determined: θ=0.24 rad, and π/6=0.52. Consequently, thefollowing relationship is satisfied: 0≤θ≤π/6.

A distance d [mm] between an end portion 22 (corner portion) of theconcave curved surface 20 of the blade portion 12 and the sputteringsurface 2 of the sputtering target 1 is represented by the formulabelow: d=Ra−Rb+a, and satisfies the relationship below: 0.05≤d.

For example, when Ra=3.5 mm, Rb=3 mm, and a=−0.4 mm, the following valueis determined: d=0.1 mm.

Consequently, the following relationship is satisfied: 0.05<d.

Further, Ra[mm], Rb[mm], a[mm], and the gap b[mm] of the first centerpoint C1 from the second center point C2 satisfy the followingrelational formula:

a=b−Ra×sin{½×sin⁻¹(1−Rb ² /Ra ²)}.

A used herein, the value “a” is a negative value when Cb is set as theorigin and C1 is located more on the inner side of the sputtering targetthan the origin Cb, and a positive value when C1 is located more on theouter side of the sputtering target than Cb. Here, the value “b” is anegative value when C2 is set as the origin and C1 is located more onthe inner side of the sputtering target than C2, and a positive valuewhen C1 is located more on the outer side of the sputtering target thanthe origin C2.

According to the above-mentioned method for processing a sputteringtarget 1, the sputtering target 1 is chamfered at the corner portion 4in such a manner that the curvature radius Ra of the concave curvedsurface 20 of the blade portion 12 is equal to or more than thecurvature radius Rb of the aimed R face 105, and preferably more thanthe curvature radius Rb on the cross section along the axis 11 a, andthe end portions 21 and 22 of the concave curved surface 20 in the bladeportion 12 are positioned away from the sputtering target 1. Thereby,when the sputtering target 1 is cut to chamfer at the corner portion 4with the concave curved surface 20 of the blade portion 12 so as to forman R face 5, the R face 5 can be approximated to an aimed R face 105 andbe prevented from being scratched the R face 5.

According to the above-mentioned method for processing a sputteringtarget 1, the following relationships are satisfied: Rb/2≤L≤Rb, 0≤θ≤π/6,and 0.05≤d. Thereby, the R face 5 can further be approximated to theaimed R face 105 and be prevented from being scratched to the R face 5.

Furthermore, the following ranges are preferably satisfied: 2Rb/3≤L≤Rb,0≤θ≤11π/90, and 0.1≤d. Thus, the R face 5 can can further beapproximated to the aimed R face 105 and be prevented from beingscratched to the R face 5.

In short, the sputtering target 1 can be cut at the corner portion 4 inany region of the concave curved surface 20 excluding the end portions21 and 22, and the R face 5 can have a smooth surface. In particular,since the R face 5 on the side of the sputtering surface 2 can beprevented from being scratched, abnormal electrical discharge can alsobe prevented during sputtering, i.e., during applying high voltagebetween the substrate and the sputtering target 1.

Further, both ends 21 and 22 of the concave curved surface 20 in theblade portion 12 can be prevented from cutting the sputtering target 1even if the sputtering target 1 is a long body having a length of, forexample, 2 m, 3 m, or more to thereby become different in shape amongsputtering targets 1. The processing method of the present invention canbe applied to processing sputtering targets, including long, rectangleor square targets, disk-shaped targets and cylindrical targets. Toexhibit the effects of the present invention, the length in thelong-side direction of the sputtering target is 1,500 mm or more and4,000 mm or less, preferably 2,000 mm or more and 3,500 mm or less, morepreferably 2,200 mm or more and 3,200 mm or less, and still morepreferably 2,500 mm or more and 2,800 mm or less. In the firstembodiment, the cutting tool 10 is arranged with respect to thesputtering target 1 such that the axis 11 a coincides with the thicknessdirection of the sputtering target 1. Alternatively, the cutting tool 10may be arranged such that the axis 11 a is positioned in parallel withthe sputtering surface 2, and may be then moved along the long-sidedirection of the sputtering target 1 (in the extending direction of thecorner portion 4), thereby making the blade portion 12 of the cuttingtool 10 to cut the corner portion 4 of the sputtering target 1.

Second Embodiment

FIG. 4 is a perspective view illustrating a second embodiment of amethod for processing a sputtering target according to the presentinvention. In the second embodiment, the same reference numerals asthose in the first embodiment denote the same components as those in thefirst embodiment, and thus their descriptions are omitted.

In the first embodiment, the processing device, such as a millingmachine, an NC milling machine, or a machining center, has beendescribed by way of example. In this processing device, the sputteringtarget is chamfered at the corner portion by rotating the cutting toolwhile fixing the sputtering target. In the second embodiment, thesputtering target is chamfered at the corner portion by rotating adisk-shaped or cylindrical sputtering target around its central axiswithout rotating a blade portion of the cutting tool.

As shown in FIG. 4, a disk-shaped sputtering target 1A is attached ontoa rotating portion 7 of the processing device, and then the rotatingportion 7 is rotated to make the sputtering target 1A rotate around thecentral axis 1 a. The central axis 1 a of the sputtering target 1A is astraight line that intersects the sputtering surface 2 perpendicularlyand passes through the center of the sputtering surface 2. As theprocessing device for chamfering, a lathe, an NC lathe, and the like canbe used.

Thereafter, the sputtering target 1A as rotating is chamfered at thecorner portion 4 between the sputtering surface 2 and side surface 3with the concave curved surface 20 of the blade portion 12 in thecutting tool 10 in such a manner that the cornea portion is approximatedto the aimed R face. A specific chamfering method in the presentembodiment is the same as that in the first embodiment. The bladeportion 12 in the cutting tool 10 can have the same shape as the cuttingtool used in the processing device of the first embodiment, such as amilling machine.

When the sputtering target 1A has a disk shape, the use of theprocessing device, such as a lathe or an NC lathe, the sputtering target1A can be processed efficiently and be prevented from being scratched.

The number of rotations around the central axis la for the sputteringtarget 1A and the feed speed of the blade portion for the cutting tool10 during chamfering may be appropriately adjusted depending on thematerial of the sputtering target 1A. Usually, the number of rotationsmay be 5 to 1000 rpm, and the tool feed speed may be 1 mm/rotation orless.

The cylindrical sputtering target can also be processed in the samemanner as the disk-shaped sputtering target. That is, the sputteringtarget is rotated around its central axis to be chamfered at the cornerportion with a cutting tool. In the cylindrical sputtering target, thesputtering surface is formed by an outer peripheral surface of acylindrical material. Each of the side surfaces is formed by a surfacein the thickness direction of the cylindrical material. The central axisof the cylindrical target is a straight line that is in parallel withthe outer peripheral surface and passes through the center of the sidesurface.

When chamfering the disk-shaped or cylindrical sputtering target, thecutting tool can be approached and contacted by setting the shaftportion of the cutting tool perpendicular to the sputtering surface orto the side surface in the sputtering target. It may be appropriatelyselected depending on the shape of the sputtering target and the type ofthe processing device.

Third Embodiment

A method for producing a sputtering target product will be described. Asputtering target is processed by the method for processing a sputteringtarget according to the first embodiment or the second embodiment toproduce a sputtering target product.

Specifically, for example, in the producing method, a target material isformed into a rectangular parallelepiped shape or a cylindrical shapethrough melting or casting. Then, the formed target material issubjected to plastic working, such as rolling, forging, or extrusion,thereby obtaining a plate-shaped or cylindrical sputtering target.Thereafter, the thus-obtained sputtering target is processed by theprocessing method. The processed plate-shaped sputtering target isjoined to a backing plate to produce a sputtering target product.

The surface of the sputtering target obtained after the processing bythe processing method and/or after the joining to the backing plate maybe subjected to finish processing as needed. The backing plate may beomitted, and only the processed sputtering target may be used to producethe sputtering target product. The joined sputtering target may beprocessed by the method for processing a sputtering target, therebyproducing the sputtering target product. In the case of the cylindricalsputtering target, an adapter for installation on a dedicated device maybe welded and attached to either one or both of the end portions of thesputtering target.

The backing plate is made of a conductive material, such as a metal oran alloy thereof. Examples of the metal include copper, aluminum andtitanium. For example, solder is used to join the sputtering target andthe backing plate. Examples of the material of the solder includemetals, such as indium, tin, zinc and lead, and alloys thereof.

Therefore, the method for producing a sputtering target product utilizesthe processing method so that the sputtering target product havingimproved quality can be provided.

The present invention is not limited to the above-mentioned embodiments,and various modifications and changes can be made to these embodimentswithout departing from the scope of the present invention.

Example 1

Example 1 is shown in Table 1. Table 1 shows the relationship among theintercept L [mm], the angle θ [rad] of the R face 5, and the gap d [mm]when changing the radius Ra [mm] of the cutting tool 10, the gap a [mm]of the first center point C1 from the center point Cb of the aimed Rface, the gap b [mm] of the first center point C1 from the second centerpoint C2. Here, the value “b” was a negative value when C2 was set asthe origin and C1 was located more on the inner side of the sputteringtarget than C2, and a positive value when C1 was located more on theouter side of the sputtering target than the origin C2.

TABLE 1 Gap a Gap b [mm] of [mm] of Distance first center first centerAngle θ d between Radius point C1 point C1 relative end portion of endfrom center from to of blade mill point Cb second sputtering portion andRa of aimed center Intercept surface sputtering [mm] R face point C2 L[mm] [rad] surface [mm] 3 0 0 3.0 0.00 0.00 0.1 0.1 2.1 0.26 0.10 0.20.2 1.7 0.37 0.20 0.3 0.3 1.4 0.45 0.30 0.4 0.4 1.1 0.52 0.40 0.5 0.50.8 0.59 0.50 3.25 −0.241 0 3.0 0.07 0.01 −0.141 0.1 2.3 0.26 0.11−0.041 0.2 1.9 0.36 0.21 0.059 0.3 1.6 0.44 0.31 0.159 0.4 1.3 0.51 0.410.259 0.5 1.0 0.57 0.51 3.5 −0.469 0 3.0 0.13 0.03 −0.369 0.1 2.4 0.270.13 −0.269 0.2 2.0 0.37 0.23 −0.169 0.3 1.7 0.44 0.33 −0.069 0.4 1.40.50 0.43 0.031 0.5 1.1 0.56 0.53 3.75 −0.687 0 3.0 0.18 0.06 −0.587 0.12.5 0.30 0.16 −0.487 0.2 2.1 0.38 0.26 −0.387 0.3 1.8 0.44 0.36 −0.2870.4 1.5 0.50 0.46 −0.187 0.5 1.2 0.56 0.56 4 −0.898 0 3.0 0.23 0.10−0.798 0.1 2.5 0.32 0.20 −0.698 0.2 2.2 0.39 0.30 −0.598 0.3 1.9 0.450.40 −0.498 0.4 1.6 0.51 0.50 −0.398 0.5 1.3 0.56 0.60 4.25 −1.104 0 3.00.26 0.15 −1.004 0.1 2.6 0.34 0.25 −0.904 0.2 2.2 0.41 0.35 −0.804 0.31.9 0.46 0.45 −0.704 0.4 1.6 0.51 0.55 −0.604 0.5 1.4 0.56 0.65 4.5−1.306 0 3.0 0.29 0.19 −1.206 0.1 2.6 0.36 0.29 −1.106 0.2 2.3 0.42 0.39−1.006 0.3 2.0 0.47 0.49 −0.906 0.4 1.7 0.52 0.59 −0.806 0.5 1.4 0.560.69

Ra was changed to 3 mm, 3.25 mm, 3.5 mm, 3.75 mm, 4 mm, 4.25 mm, and 4.5mm. Rb was set to 3 mm. In addition, b was changed to 0 mm, 0.1 mm, 0.2mm, and 0.3 mm with the second center point C2 used as the reference ineach Ra.

The intercept L, the angle θ of the R face, and the gap d will bedescribed with reference to an enlarged view of the sputtering target 1in FIG. 5.

The aimed R face 105 is indicated by a dashed-two dotted line. A square100 with one side Rb is defined such that an arc line of the aimed Rface 105 intersects with the vertices of the diagonal line of the square100. This square 100 is indicated by a dotted line. The first side 101of the four sides of the square 100, which is located outside thesputtering target 1, contacts the sputtering surface 2.

The intercept L and the angle θ will be described below. The intercept Lis defined as a length of a part of the first side 101 located outsidethe R face 5. The angle θ of the R face is defined as an angle formedbetween a line as a part of the first side 101 located outside the Rface 5 and the R face 5.

The gap d will be described below. As shown in FIG. 3, the gap d isdefined as a distance between each of both ends 21 and 22 of the concavecurved surface 20 and the sputtering target 1.

Tables 2 to 4 are made based on Table 1. Table 2 shows the relationshipbetween Ra and b and the intercept L; Table 3 shows the relationshipbetween Ra and b and the angle θ of the R face; and Table 4 shows therelationship between Ra and b and the gap d.

In Tables 2 to 4, the ranges enclosed by frames indicate ranges in whichthe R face 5 could approach the aimed R face 105 while securing thedistance between each of the end portions 21 and 22 of the concavecurved surface 20 and the sputtering target 1.

Specifically, in Tables 2 and 3, the ranges enclosed by solid linesindicate ranges of L and θ specified by the embodiment of the presentapplication, respectively, and the ranges enclosed by dashed-dottedlines indicate preferable ranges of L and θ, respectively.

In Table 4, the range enclosed by the solid line indicates the range ofd specified by the embodiment of the present application, and the rangeenclosed by the dashed-dotted line indicates a preferable range of d.Furthermore, the range enclosed by the dashed-two dotted line indicatesa range where all the specified ranges of d, θ and L overlap oneanother, and the range enclosed by the dotted line indicates a rangewhere all the preferable ranges of d, θ and L overlap one another.

As shown in Table 4, when Ra=3 and b=0, the distance d resulted ind=0.00. Here, both ends 21 and 22 of the concave curved surface 20 inthe blade portion 12 were in contact with the sputtering target 1, butit was found that the end portions 21 and 22 of the concave curvedsurface 20 in the blade portion 12 cut into the sputtering target 1 dueto slight variations during the processing treatment, such as distortionof the material of the sputtering target 1 or runout of the bladeportion 12, resulting in scratching the sputtering target 1 with a veryhigh possibility. It was supposed that when the distance d was set to0.05 or more, the end portions 21 and 22 of the blade portion 12 wassuppressed to contact or cut and scratch the sputtering target 1, evenif the distortion of the material or runout of the blade portion 12occurs.

As shown in Tables 1 to 4, when the following relationships weresatisfied: Rb/2≤L≤Rb, 0≤θ≤π/6, and 0.05≤d, the R face 5 could beapproximated to an aimed R face 105 and could easily be prevented frombeing scratched.

Example 2

In Example 2, the values Ra and Rb were different from those inExample 1. Specifically, in Example 2, the sputtering target wasprocessed on the same conditions as those in Example 1 except that Rawas changed to 2 mm, 2.25 mm, 2.5 mm, 2.75 mm, 3 mm, 3.25 mm, and 3.5mm. Rb was set at 2 mm.

Table 5 shows the relationship between Ra and b and the intercept L;Table 6 shows the relationship between Ra and b and the angle θ of the Rface; and Table 7 shows the relationship between Ra and b and the gap d.

As shown in Tables 5 to 7, when the following relationships weresatisfied: Rb/2≤L≤Rb, 0≤θ≤π/6, and 0.05≤d, the R face 5 could beapproximated to an aimed R face 105 and could easily be prevented frombe scratched.

Specifically, in Tables 5 and 6, the ranges enclosed by the solid linesindicate ranges of L and θ specified by the embodiment of the presentapplication, respectively, and the ranges enclosed by the dashed-dottedlines indicate preferable ranges of L and θ, respectively.

In Table 7, the range enclosed by the solid line indicates the range ofd specified by the embodiment of the present application, and the rangeenclosed by the dashed-dotted line indicates a preferable range of d.Furthermore, the range enclosed by the dashed-two dotted line indicatesa range where all the specified ranges of d, θ and L overlap oneanother, and the range enclosed by the dotted line indicates a rangewhere all the preferable ranges of d, θ and L overlap one another.

Example 3

In Example 3, the sputtering target was processed on the same conditionsas those in Example 1 except that the values Ra and Rb were different.Ra was changed to 4 mm, 4.25 mm, 4.5 mm, 4.75 mm, 5 mm, 5.25 mm, and 5.5mm. Rb was set at 4 mm.

Table 8 shows the relationship between Ra and b and the intercept L;Table 9 shows the relationship between Ra and b and the angle θ of the Rface; and Table 10 shows the relationship between Ra and b and the gapd.

As shown in Tables 8 to 10, when the following relationships weresatisfied: Rb/2≤L Rb, 0≤θ≤π/6, and 0.05≤d, the R face 5 could beapproximated to an aimed R face 105 and could easily be prevented frombe scratched. Specifically, in Tables 8 and 9, the ranges enclosed bythe solid lines indicate ranges of L and θ specified by the embodimentof the present application, respectively, and the ranges enclosed by thedashed-dotted lines indicate preferable ranges of L and θ, respectively.

In Table 10, the range enclosed by the solid line indicates the range ofd specified by the embodiment of the present application, and the rangeenclosed by the dashed-dotted line indicates a preferable range of d.Furthermore, the range enclosed by the dashed-two dotted line indicatesa range where all the specified ranges of d, θ and L overlap oneanother, and the range enclosed by the dotted line indicates a rangewhere all the preferable ranges of d, θ and L overlap one another.

Experiment

Next, experimental data about Examples of the present application willbe described. A rolled plate made of high-purity Al, which had a purityof 99.999%, was prepared. Cutting processing was performed on the rolledplate by installing a cutter for surface processing and an end mill forside surface processing on a double column type machining center,thereby obtaining a sputtering target material having a long side of2300 mm in length and a short side of 190 mm in length. Then, a cuttingtool (R cutter) for R processing was fixed to the double column typemachining center, and subsequently a corner portion of the sputteringtarget material was processed by the cutting tool under the processingconditions including the number of rotations of 8000 rpm and the toolfeed speed of 1000 mm/min, whereby a sputtering target was finallyobtained. Here, when the processing was performed on the corner portionby setting Ra=3.25, Rb=3, and a=0.009 (b=0.25), a defect rate ofscratching the sputtering target by the end portion of the blade was 0%.When the processing was performed on the corner portion by settingRa=3.5, Rb=3, and a=−0.369 (b=0.1), a defect rate of scratching thesputtering target by the end portion of the blade was 0%.

DESCRIPTION OF REFERENCE NUMERALS

-   1, 1A Sputtering target-   1 a Central axis-   2 Sputtering surface-   3 Side surface-   4 Corner portion-   5 R face-   10 Cutting tool-   11 Shaft portion-   11 a Axis-   12 Blade portion-   20 Concave curved surface-   21 First end-   22 Second end-   30 Side surface-   31 Leading end surface-   105 Aimed R face-   C1 First center point-   C2 Second center point-   Cb Center of aimed R face-   d Gap between each of both ends of the concave curved surface and    the sputtering target-   Ra Curvature radius of the concave curved surface in the blade    portion in the cutting tool-   Rb Curvature radius of the aimed R face of the sputtering target

1. A method for processing a sputtering target comprising: processing asputtering target by rotating a cutting tool which has a blade portionwith an arc-shaped concave curved surface on a cross section along anaxis, around the axis thereof, to chamfer the target at a corner portionbetween a sputtering surface and a side surface in the sputtering targetwith the arc-shaped concave curved surface of the blade portion in sucha manner that the corner portion gets approximated to an arc-shapedaimed R face, wherein the sputtering target is chamfered at the cornerportion in such a manner that a curvature radius Ra of the concavecurved surface in the blade portion is more than a curvature radius Rbof the aimed R face on the cross section along the axis and that bothends of the concave curved surface in the blade portion are positionedaway from the sputtering target.
 2. (canceled)
 3. A method forprocessing a sputtering target, comprising: processing a disk-shaped orcylindrical sputtering target by rotating the target around the centralaxis thereof to chamfer the target at a corner portion between asputtering surface and a side surface in the rotating sputtering targetwith an arc-shaped concave curved surface of a blade portion in such amanner that the corner portion gets approximated to an arc-shaped aimedR face, wherein the sputtering target is chamfered at the corner portionin such a manner that a curvature radius Ra of the concave curvedsurface is more than a curvature radius Rb of the aimed R face and thatboth ends of the concave curved surface in the blade portion werepositioned away from the sputtering target.
 4. (canceled)
 5. The methodaccording to claim 1, wherein the sputtering target is chamfered at thecorner portion in such a manner that both the ends of the concave curvedsurface in the blade portion are positioned away from the sputteringtarget, and wherein, in a coordinate system in which a center point Cbof the aimed R face is set as an origin, a [mm] is a gap of a firstcenter point C1 of the concave curved surface with the curvature radiusRa of the blade portion from the center point Cb of the aimed R face ineach of horizontal and vertical directions on the coordinate system, Ra,Rb, and a are set to satisfy the following conditions: with regard to anintercept L [mm] of an R face, the relationship of Rb/2≤L≤Rb issatisfied when L is represented by the formula ofL=Rb−Ra{1−(Rb−a)²}^(1/2)−a; with regard to an angle θ [rad] formedbetween the sputtering surface of the sputtering target and an endportion of the R face of the sputtering target, the relationship of0≤θ≤π/6 is satisfied when the angle θ [rad] is represented by theformula of θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2); and and with regard to adistance d [mm] between an end portion of the concave curved surface inthe blade portion and the sputtering surface of the sputtering target,the relationship of 0.05≤d is satisfied when the distance d [mm] isrepresented by the formula of d=Ra−Rb+a.
 6. A method for producing asputtering target product, comprising: processing a sputtering targetusing the method according to claim 1 to producing the sputtering targetproduct.
 7. The method according to claim 3, wherein the sputteringtarget is chamfered at the corner portion in such a manner that both theends of the concave curved surface in the blade portion are positionedaway from the sputtering target, and wherein, in a coordinate system inwhich a center point Cb of the aimed R face is set as an origin, a [mm]is a gap of a first center point C1 of the concave curved surface withthe curvature radius Ra of the blade portion from the center point Cb ofthe aimed R face in each of horizontal and vertical directions on thecoordinate system, Ra, Rb, and a are set to satisfy the followingconditions: with regard to an intercept L [mm] of an R face, therelationship of Rb/2≤L≤Rb is satisfied when L is represented by theformula of L=Rb−Ra{1−(Rb−a)²/Ra²}^(1/2)−a; with regard to an angle θ[rad] formed between the sputtering surface of the sputtering target andan end portion of the R face of the sputtering target, the relationshipof 0≤θ≤π/6 is satisfied when the angle θ [rad] is represented by theformula of θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2); and and with regard to adistance d [mm] between an end portion of the concave curved surface inthe blade portion and the sputtering surface of the sputtering target,the relationship of 0.05≤d is satisfied when the distance d [mm] isrepresented by the formula of d=Ra−Rb+a.
 8. A method for producing asputtering target product, comprising: processing a sputtering targetusing the method according to claim 3 to producing the sputtering targetproduct.
 9. A method for processing a sputtering target comprising:processing a sputtering target by rotating a cutting tool which has ablade portion with an arc-shaped concave curved surface on a crosssection along an axis, around the axis thereof, to chamfer the target ata corner portion between a sputtering surface and a side surface in thesputtering target with the arc-shaped concave curved surface of theblade portion in such a manner that the corner portion gets approximatedto an arc-shaped aimed R face, wherein the sputtering target ischamfered at the corner portion in such a manner that both ends of theconcave curved surface of the blade portion are positioned away from thesputtering target, and wherein, in a coordinate system in which a centerpoint Cb of the aimed R face with the curvature radius Rb is set as anorigin, a [mm] is a gap of a first center point C1 of the concave curvedsurface with the curvature radius Ra of the blade portion from thecenter point Cb in each of horizontal and vertical directions on thecoordinate system, Ra, Rb, and a are set to satisfy the followingconditions: with regard to an intercept L [mm] of an R face, therelationship of Rb/2≤L≤Rb is satisfied when L is represented by theformula of L=Rb−Ra{1−(Rb−a)²/Ra²}^(1/2)−a; with regard to an angle θ[rad] formed between the sputtering surface of the sputtering target andan end portion of the R face of the sputtering target, the relationshipof 0≤θ≤π/6 is satisfied when the angle θ [rad] is represented by theformula of θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2); and with regard to adistance d [mm] between an end portion of the concave curved surface ofthe blade portion and the sputtering surface of the sputtering target,the relationship of 0.05≤d is satisfied when the distance d [mm] isrepresented by the formula of d=Ra−Rb+a.
 10. A method for processing asputtering target, comprising: processing a disk-shaped or cylindricalsputtering target by rotating the target around a central axis thereofto chamfer the target at a corner portion between a sputtering surfaceand a side surface in the rotating sputtering target with an arc-shapedconcave curved surface of a blade portion in such a manner that thecorner portion gets approximated to an arc-shaped aimed R face, whereinthe corner portion of the sputtering target is chamfered in such amanner that both ends of the concave curved surface of the blade portionwere positioned away from the sputtering target, and wherein, in acoordinate system in which a center point Cb of the aimed R face withthe curvature radius Rb is set as an origin, a [mm] is a gap of a firstcenter point C1 of the concave curved surface with the curvature radiusRa of the blade portion from the center point Cb in each of horizontaland vertical directions on the coordinate system, Ra, Rb, and a are setto satisfy the following conditions: with regard to an intercept L [mm]of an R face, the relationship of Rb/2≤L≤Rb is satisfied when L isrepresented by the formula of L=Rb−Ra{1−(Rb−a)²/Ra²}^(1/2)−a; withregard to an angle θ [rad] formed between the sputtering surface of thesputtering target and an end portion of the R face of the sputteringtarget, the relationship of 0≤θ≤π/6 is satisfied when the angle θ [rad]is represented by the formula of θ=π/2−cos⁻¹{1−(Rb−a)²/Ra²}^(1/2); andwith regard to a distance d [mm] between an end portion of the concavecurved surface of the blade portion and the sputtering surface of thesputtering target, the relationship of 0.05≤d is satisfied when thedistance d [mm] is represented by the formula of d=Ra−Rb+a.
 11. A methodfor producing a sputtering target product, comprising: processing asputtering target using the method according to claim 9 to producing thesputtering target product.
 12. A method for producing a sputteringtarget product, comprising: processing a sputtering target using themethod according to claim 10 to producing the sputtering target product.